In a mixing bowl whisk flour, baking powder and salt together. Add warm milk and melted butter; stir until a shaggy dough forms. Turn out onto floured surface and knead briefly until mostly smooth. Cover and let rest 10‑15 minutes.

Divide dough into 8 equal balls. Roll each into a circle about 6 inches wide and approx. ⅛‑inch thick.

Heat about 2 inches of oil in a large pot to ~ 350°F (175°C). Fry one dough circle at a time: drop into hot oil for ~5 seconds per side just to puff, then use tongs to fold gently in half and hold in oil for ~1‑2 minutes per side until golden brown and crisp. Drain on paper towels.

In a skillet over medium‑high heat, sauté onion until softened. Add ground beef, cook until browned. Drain excess fat if needed. Stir in taco seasoning (or chili powder, cumin, garlic powder) plus a splash of water. Simmer 3‑5 minutes until flavors combine.

Fill each warm shell with a scoop of beef, sprinkle shredded cheese, add lettuce, tomato, sour cream and a drizzle of taco sauce. Serve immediately.